Device and method for carrying out spatially directed detection of an electroencephalogram

ABSTRACT

The invention concerns an arrangement and a procedure for the spatial directed capturing of the electro encephalogram from selected brain areas with electrodes that are attached on the skull surface of an examined person.  
     According to the invention, several electrodes are arranged on the skull surface in such a way, that a part of the electrodes capture the electrical activity generated from the targeted brain area. Another part of the electrodes captures the electrical activity from the targeted area and the disturbing electrical activity generated by the adjacent areas. This is considerably reduced with the help of an electronic circuit and methods of signal processing.

SCOPE OF THE INVENTION

[0001] The invention concerns an arrangement and a procedure for thespatial directed capturing of the electro encephalogram from selectedbrain areas.

LATEST TECHNOLOGY

[0002] The latest technology knows systems that capture the EEG withsuitable electrodes at pre-defined standardized positions and feed it toan amplifier. The disadvantageous effect is that the electrical activitycan only be captured from relatively large areas of the brain.

[0003] But in many medical problems of neurology, physiology or thefunction diagnostic the local brain activity of certain anatomicallimited areas or centers is of more essential significance. A series ofextensive signal processing steps is necessary to capture the electricalactivity of such areas and to free them from disturbances by theadjacent brain areas. For that the amplified EEG must be digitalized andafterwards analyzed in a computer.

[0004] A big disadvantage of this procedure is that only an offlineanalysis is possible. Therefore, this procedure can not be used in timecritical procedures either.

DESCRIPTION OF THE INVENTION

[0005] The task of the invention is therefore to supply a procedure andan arrangement in which the local electrical activity of a spatiallimited brain area is captured and can be used for further processingand/or analysis. At the same time the affecting and disrupting fieldsfrom the adjacent brain areas on the desired area to be examined shallbe considerably suppressed in their projection on the deviatedpotential.

[0006] According to the invention, it is intended with an arrangementfor the spatial directed capturing of an electro encephalogram, in whichelectrodes are attached to the skull surface of the examined person,that

[0007] parts of the electrodes are arranged in such a way that theycapture the activity of the targeted cortical structure, and

[0008] other parts of the electrodes are arranged in such a way thatthey capture the activity of the targeted cortical structure and theactivity of the surrounding areas and furthermore

[0009] an electronic evaluation circuit exists.

[0010] In an advantageous advancement of the arrangement according tothe invention, the electrodes are axial symmetrically arranged around areference electrode in an inner ring and an outer ring.

[0011] The invention furthermore concerns a procedure for the spatialdirected capturing of the electro encephalogram, in which the electricalactivity is measured

[0012] over the targeted cortical structure as well as

[0013] over the targeted cortical structure and the adjacent area and

[0014] the received potentials are amplified and feed to an electricalcircuit.

[0015] In an advantageous advancement of the procedure according to theinvention it is intended that the spatial directional pattern for thecapturing of the activity of a targeted cortical structure is realizedwith algorisms of the signal processing.

[0016] The arrangement on hand, according to the invention, and theprocedure belonging to it is characterized in a way that the electricalactivity of the targeted brain area is freed from disturbancessimultaneously to the EEG capturing. In traditional capturing methodsthis is only possible with the help of offline analyzes, meaning withmethods of signal processing that are based on several repetitions ofthe measurement and are therefore clinically realized in a lot of caseswith unacceptable delays.

SHORT DESCRIPTION OF THE DRAWING

[0017] In the following the invention is explained with the help of adrawing that shows the general design of a spatial directed EEGcapturing.

DETAILED DESCRIPTION OF THE DRAWING

[0018] The arrangement shown can be used for the examination on thevisual cortex. A double ring is attached on the skull surface over thevisual cortex of the patient above the inion 4. The number of the usedelectrodes depends on the respective technical equipment. They are axialsymmetrically arranged around the reference electrode 1.

[0019] The inner electrode ring 2 is positioned directly above the ROI(region of interest—the target area). Its measurements have to beselected depending on the known anatomical characteristics.

[0020] The outer electrode ring 3 additionally covers the activity ofthe areas surrounding the ROI. The electrode potentials of the innerring 2 and the outer ring 3 are amplified with common EEG amplifiers 5and 6 and fed to the electronic block 7. The electrical directionpattern of the electrodes configuration and the interference suppressionof adjacent brain areas is realized with a suitable analog and digitalcircuit technology as well as algorithm implemented in a microcontroller or signal processor. The formed difference of the activitiesof both brain volumes creates an almost undisturbed activity of theexamined area (ROI). The examined person can already receivediagnostically relevant information during the reception of the brainpotentials.

1. Arrangement for the spatial directed capturing of an electroencephalogram with electrodes attached on the skull surface of anexamined person, characterized in a way, that a part of the electrodesare arranged in such a way that they capture the activity of thetargeted cortical structure, another part of the electrodes in such away that they capture the activity of the targeted cortical structureand the surrounding areas and that an electronic evaluation circuitexists. Arrangement according to claim 1, characterized in a way, thatthe electrodes are axial symmetrically arranged around a referenceelectrode (1) in an inner ring (2) and an outer ring (3). Procedure forthe spatial directed capturing of an electro encephalogram,characterized in a way, that the electrical activity is captured overthe targeted cortical structure and over the targeted cortical structureand the adjacent areas and that the received potentials are amplifiedand fed to an electronic circuit. Procedure according to claim 3,characterized in a way, that the cortical direction characteristic forthe capturing of the activity of a targeted cortical structure isrealized with algorithm of the signal processing.